Ships constructed on or after January 1, 2016 and entering into the North American or U.S. Caribbean Emission Control Areas (ECA) must comply with the Tier III NOx requirement of MARPOL Annex VI, Chapter 3, Regulation 13.5.1.1.

This affects any ship whose keel is laid or where the vessel is at a similar stage of construction. The regulatory change also applies to a major conversion defined in Regulation 13. The standards set forth in Regulation 13.5.1.1 will not apply to marine diesel engines installed on a ship with a combined nameplate diesel engine propulsion power of less than 750 kW if it is demonstrated to the satisfaction of the administration and cannot comply with the standards set forth (in paragraph 5.1.1 of Regulation 13) because of design or construction limitations of the ship.

Additionally, the standards will not apply to vessels less than 24 meters in length specifically designed, and solely used, for recreational purposes. This includes vessels specifically designed, and solely used, for recreational purposes of less than 500 GT with a length of 24 meters or more and constructed prior to January 1, 2021.
Currently no other ECA has NOx Tier III compliance requirements. Compliance is also required for ships operating in an emission control area that is eventually designated for Tier III NOx (other than the North American or Caribbean ECAs). In such a case, a later date may be specified in the amendment designating the NOx Tier III emission control area.
Failure to comply with the NOx Tier III requirements would be a violation of the Act to Prevent Pollution From Ships (APPS). This could result in civil penalties of $25,000 per violation with each day of a continuing violation considered a separate violation. Additional civil penalties of $5000 per day may be applied for false statements or other fraudulent representation of a continuing violation. Vessels may be liable in rem and may be prosecuted in Federal Court. Finally, vessel clearance may be revoked and a surety bond may be required to sail.